Emulsions as delivery systems

Emulsion-based delivery systems (EBDS) has been introduced as successful carrier systems for BLI. Eor example, co-3 fatty acid-rich TAGs were incorporated as emulsions into different food products, such as milk, yogurts, ice cream, and meat patties (Chee et al., 2005,2007 Lee et al, 2005,2006a, 2006b McClements and Decker, 2000 Sharma, 2005). 

Other BLI have been dissolved in carrier lipids prior to emulsification, for example lycopene (Ribeiro et al, 2006 Tyssandier et al, 2001), astaxanthin (Ribeiro et ah, 2005, 2006), lutein (Losso et al, 2005 Santipanichwong and Suphantharika, 2007), p-carotene (Santipanichwong and Suphantharika, 2007), and plant sterols (Sharma, 2005). As noted above, the delivery system must chemically stabilize the BLI without impairing bioavailability. 

Many emulsified lipids and encapsulated BLI are vulnerable to chemical destruction most commonly via oxidative reactions or acid hydrolysis. The structure of the emulsion and the microlocalization of the BLI affect the rate of chemical degradation. It is also important to consider the relative localization of any other reagents (e.g., oxygen, protons), catalysts (e.g., transition metals), and inhibitors of oxidation reactions (e.g., antioxidants) involved in the BLI degradation reaction. 

Other studies have demonstrated the importance that droplet charge has on lipid oxidation kinetics in oil-in-water emulsions (McClements and Decker, 2000 Hu et al., 2003 Klinkesom et al., 2005 Mei et al., 1998a, 1998b). In a similar study. Boon and co-workers (2008) showed that the oxidative stability of lycopene emulsions is higher when stabilized with cationic and non-ionic surfactants than in emulsions stabilized with anionic surfactants. 

The interfacial thickness of emulsion droplets is an important parameter affecting lipid oxidation reaction rates. Increasing interfacial membrane thickness can conceivably hinder the physical interaction between aqueous phase prooxidants (e.g., transition metals) and emulsified lipids(Chaiyasit et al., 2000 Silvestre et al., 2000). For example, Silvestre and co-workers (2000) showed that iron-catalyzed cumenehydroperoxide reduction, as well as salmon oil-in-water emulsion oxidation, was slower when Brij 700 was used in place of Brij 76. Brij 700 and 76 are small molecule surfactants with identical hydrophobic tail group lengths (CHjlCH lj -), but vary only with respect to the size of their polar head groups Brij 700 and Brij 76 consist of 100 and 10 oxyethylene head groups, respectively. Lower hydroperoxide decomposition and lipid oxidation rates in Brij 700-stabilized emulsions suggest that a thicker interfacial layer was able to act as a physical barrier to decrease lipid-prooxidant interactions (Silvestre et al., 2000). 

---

Cascone MG, Lazzeri L, Carmignani C, Zhu ZH (2002) Gelatin nanoparticles produced by a simple W/O emulsion as delivery system for methotrexate. J Mater Sci Mater Med 13(5) 523-526... 

Appelqvist, I.A.M. Golding, M. Vreeker, R. Zuidam, N.J. Emulsions as delivery systems in foods. In Lakkis, J.M. (Ed.) Encapsulation and Controlled Release Technologies in Food Systems, Blackwell Publishing, Ames, lA, 2007, pp. 41-81. 

---